PROJECT SUMMARY A primary aim of PAR-15-359 ?Novel Approaches to Diagnosing Alzheimer's Disease & Predicting Progression? is to ?identify new biomarkers that are minimally invasive, inexpensive and that could be used for screening a general population.? Further, this PAR states that ?A biomarker that could be used for screening in primary-care settings would be particularly useful.? The Centers for Medicare & Medicaid Services (CMS) Annual Wellness Visit (AWV) includes a cognitive examination (CMS.gov); however, the 2015 Gerontological Society of American working group reported that ?older adults are inadequately assessed for cognitive impairment during routine visits with their primary care providers?. This report further states that without a diagnosis, individuals with AD do not ?benefit from post-diagnostic medical care? that can ?lead to improved health-related outcomes and well-being?. Here we propose the first-ever examination of an AD Blood Test as the first-step in this multi-tier diagnostic process beginning in primary care. The PIs are global experts in blood-based biomarkers of AD and longitudinal studies of AD. PI O'Bryant has followed the Institute of Medicine (IOM) guidelines for the development and validation of the AD Blood Test, which has been validated across cohorts, assay platforms, tissues type, animal models, and ethnicities. We will leverage a substantial existing infrastructure and resources to address the following Specific Aims: Aim 1: Validate the Alzheimer's Blood Test in Primary Care Settings; Aim 2: Validate the Alzheimer's Blood Test for the Detection of Prodromal AD in Primary Care Settings. The current proposal is highly significant for several reasons: (1) The AD Blood Test will provide primary care providers globally with a cost-effective means for detecting AD in routine clinical practice by selecting only those patients that require additional costly and invasive follow-up confirmatory diagnostic procedures; (2) The AD Blood Test will provide a means for reducing screening costs in prevention trials by over 50%; and finally (3) The AD Blood Test will provide a rapidly scalable means for increasing access to novel therapies globally once Regulatory approval is obtained.